I don't think it will be as simple as that actually. Assuming op is trying to dose liquid ferts directly into the substrate. You would first have to work out the volume of the syringe and the volume of the air line tubing used depending on the length. Too small a syringe with too long tubing you will probably find the ferts never leave the tube.

I discovered this recently when the air had came out of my drop checker. Rather than take the light and lid off my tank and removed the DC I decided to do a similar thing but use it to blow some air into it. The air bubble never made it to the end of the pipe.

I don't think it will be as simple as that actually. Assuming op is trying to dose liquid ferts directly into the substrate. You would first have to work out the volume of the syringe and the volume of the air line tubing used depending on the length. Too small a syringe with too long tubing you will probably find the ferts never leave the tube.

I discovered this recently when the air had came out of my drop checker. Rather than take the light and lid off my tank and removed the DC I decided to do a similar thing but use it to blow some air into it. The air bubble never made it to the end of the pipe.

Click to expand...

?
If you mix the fertiliser first then suck it up with the adapted syringe you will have fertiliser in the tube & syringe.
It shouldn't be difficult to measure out an amount of liquid say 500ml suck up a syringe full & see what's left. Syringes are calibrated.
Or am I missing something?

I think the guy in the vid is using one of these. I have one for spot dosing algae. I think that's what he's doing. Probably has h2o2 in it.
It has other uses too (like blowing air into the sand against the front glass to clean it.

But acyualy they are Kitchen / cooking supplies and some smart thinking and aquarium (shop) keeper saw grandma sedating the turkey one day and thought "Eureka!!" Another thing to sell!! So, look for liquid injectors at the local cooking equipment store..

Tho me too i do not see why it should be so much more succesfull to add lequid ferts into the substrate. Have no expernience with it..

?
If you mix the fertiliser first then suck it up with the adapted syringe you will have fertiliser in the tube & syringe.
It shouldn't be difficult to measure out an amount of liquid say 500ml suck up a syringe full & see what's left. Syringes are calibrated.
Or am I missing something?

Click to expand...

I think you're right kipper. Maybe I was filling the syringe without the tube on then trying to pump air down. In my case by the time the syringe was plunged the air hadn't left the tubing rather just filled it with air. Having the tubing on prior to sucking up would have gave different results.